Journal of Archaeological Science 67 (2016) 80e92

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Journal of Archaeological Science

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Tin ingots from a probable Bronze Age shipwreck off the coast of , : Composition and microstructure

* Quanyu Wang a, , Stanislav Strekopytov b, Benjamin W. Roberts c, Neil Wilkin d a Department of Conservation and Scientific Research, the British Museum, Great Russell Street, London, WC1B 3DG, UK b Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK c Department of Archaeology, Durham University, South Road, Durham, DH1 3LE, UK d Department of Britain, Europe and Prehistory, the British Museum, Great Russell Street, London, WC1B 3DG, UK article info abstract

Article history: The seabed site of a probable Bronze Age shipwreck off the coast of Salcombe in south-west was Received 5 November 2015 explored between 1977 and 2013. Nearly 400 objects including copper and tin ingots, bronze artefacts/ Received in revised form fragments and gold ornaments were found. The Salcombe tin ingots provided a wonderful opportunity 5 January 2016 for the technical study of prehistoric tin, which has been scarce. The chemical compositions of all the tin Accepted 8 January 2016 ingots were analysed using inductively coupled plasma mass spectrometry (ICP-MS) and inductively Available online xxx coupled plasma atomic emission spectroscopy (ICP-AES). Following the compositional analysis, micro- structural study was carried out on eight Salcombe ingots selected to cover those with different sizes, Keywords: Tin ingots shapes and variable impurity levels and also on the two Erme ingots using metallography and Bronze Age scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS). An Salcombe extensive overview of archaeological tin in Europe is also provided. ICP-MS All the Salcombe tin ingots analysed appeared to be quite pure with little variation in composition Trace elements between them. Only two samples were found to contain over 0.1% iron and one contains over 0.1% copper. The compositions of the Salcombe tin ingots have been compared to the very few compositional analyses of tin objects found elsewhere such as the Late Bronze Age shipwreck of Uluburun but do not seem to have any connection between them. Further studies including lead and tin isotope analysis are needed to answer the question of provenance of the tin ingots, so as to contribute to the study of metal trading. © 2016 Elsevier Ltd. All rights reserved.

1. Introduction bronze objects to archaeological scholarship in analysing chronol- ogy, trade, warfare, craft production and ritual (Roberts and The extraction and movement of tin throughout Europe and Thornton, 2014). The relative abundance of tin ore sources in beyond during the Bronze Age (c. 2200e800 BC) has been inves- Atlantic Europe, especially in southwest England, northwest France tigated and discussed extensively for over a century (Baer, 1876; and Iberia as well as sources in Central Europe, especially the Erz- Dayton, 1971; Franklin et al., 1978; Muhly, 1985, 1993; gebirge mountains (spanning Germany and the Czech Republic), Penhallurik, 1986; Pernicka, 1990, 1998; Pare, 2000; Giumlia-Mair has consistently enticed archaeologists and archaeometallurgists. and Lo Schiavo, 2003; Pigott, 2011). The ‘tin trade’ continues to However, there are still no radiocarbon dated Bronze Age tin mines play a key role in socio-economic models of Bronze Age societies in in Europe (Roden, 1985; Pernicka, 1998) in contrast to the extensive Europe and the Near East (Sherratt, 1993; Kristiansen and Larsson, evidence for Bronze Age copper mining (O'Brien, 2014) and recent 2005; Harding, 2013). This is due to the ubiquity of Bronze Age discoveries of Bronze Age tin mines at Kültepe, Turkey (Yener et al., bronze objects across Europe and Asia, the highly unequal distri- 2015), Deh Hosein, Iran (Nezafati et al., 2009) and in Central Asia bution of tin ore sources, and the fundamental importance of (Stollner€ et al., 2011; Garner 2015). The archaeological evidence for potential sites of tin ore extraction relies upon associated Bronze Age material culture or settlement activity as at San Cristobal de Logrosan, Spain (Merideth, 1998; Rodríguez Díaz et al., 2013) and * Corresponding author. Mt. Cer, Serbia (Huska et al., 2014). The use of trace element data as E-mail address: [email protected] (Q. Wang). http://dx.doi.org/10.1016/j.jas.2016.01.018 0305-4403/© 2016 Elsevier Ltd. All rights reserved. Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92 81

well as lead and tin isotope compositions provide insights into the provenance and can be especially useful in excluding potential tin sources, as demonstrated by the continued absence of any evidence for Bronze Age tin extraction in the Erzgebirge mountains (Niederschlag et al., 2003; Haustein et al., 2010). The evidence for Bronze Age tin smelting sites in Europe remains restricted to several fragmentary finds of tin smelting slags e although this is potentially due to the purity of the tin ores (Muhly, 1985; Malham, 2010). There have been discoveries of Bronze Age tin ingots in the east Mediterranean, and especially at shipwreck sites such as Uluburun at the southern coast of Anatolia (Pulak, 2000a; Hauptmann et al., 2002; Pulak, 2010), Cape Gelidonya (Bass, 1967, 2010) and Haifa (Stos-Gale et al., 1998). However, recent surveys of Bronze Age tin objects e as opposed to tin used in metal alloys or tin used as an inlay in other materials e across Western, Northern and Central Europe have collectively recorded less than 300 objects with the vast majority being small beads, pendants and other or- naments. However, this striking lack of Bronze Age tin objects could be primarily due to the corrosion of tin metal to tin oxide powder, especially in buried terrestrial environments (Turgoose, 1985), but potentially to a lesser degree in submarine seawater environments Fig. 1. The Salcombe site (redrawn by Craig Williams, British Museum after Needham (Memet, 2014). Hence, whilst there are numerous publications on et al., 2013, Fig. 1.10).

Fig. 2. Metalwork finds of 2005e2009 from Salcombe. 82 Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92 the Bronze Age mining and trade of tin, technical studies of tin from terrestrial sites containing comparable metalwork, placed the objects are still relatively rare (Hauptmann et al., 2002; Stos-Gale Salcombe assemblage in the Middle Bronze Age Penard metalwork et al., 1998; Valera and Valera, 2003; Cahill, 2009; Haustein et al., phase (c. 1300e1150 BC) with the exception of one Type Nantes 2010; Krüger et al., 2012; Nielsen, 2014; Ling et al. 2014). bronze sword which typologically dated to the Late Bronze Age The Salcombe site actually comprises two named sites 400 m Ewart Park metalwork phase (c. 1000e800 BC) (Needham and apart within an open bay at the mouth of an estuary e Moor Sand Giardino, 2008; Needham et al., 2013; Brandherm and Moskal-del and Salcombe B e where two groups of Bronze Age objects have Hoyo, 2014). Compositional analysis revealed that the bronzes been found between 50 and 400 m off the coastline (Fig. 1). were consistent with this dating as well as a high level of purity in Archaeological work at Moor Sand occurred between 1977 and the tin lump (Northover, 2013). The analysis of the sea level history 1982, led by Philip Baker and Keith Muckelroy (Muckelroy, 1980, and coastal geomorphology demonstrates that coastal retreat 1981), whilst work on Salcombe site B started in 2004 by the cannot explain the distribution of the metalwork and it is therefore South West Maritime Archaeology Group (www.swmag.org) and argued that the objects were transported to their location before remains ongoing. The early excavations (1977e2004) at the Sal- being dispersed on the seabed (Needham et al., 2013). The preva- combe (Moor Sand and Salcombe site B) have been recently pub- lence of later shipwrecks e Salcombe B was only found due to the lished with extensive environmental, archaeometallurgical and investigation of a 17th century AD shipwreck site termed Salcombe archaeological analyses. They recovered 31 objects including A e makes an accidental shipwreck or deliberate/votive shipwreck bronze objects of 22 weapons/fragments, one palstave-adze, one with objects eventually dispersed across the Moor Sand and Sal- cauldron handle, one rectangular block/weight, one Sicilian stru- combe B sites. However, the presence of Bronze Age metalwork mento con immanicatura a cannone, three gold objects/fragments, which is conventionally dated two centuries apart also implies two an iron awl with a bone handle and a tin lump (Needham et al., distinct events (Needham et al., 2013). 2013). In the absence of surviving organic material suitable for The 2005e2013 finds include 280 copper or copper alloy and 40 radiocarbon dating, detailed typo-chronological analyses of diag- tin bun-shaped ingots, 15 bronze objects and nine gold ornaments nostic bronze and gold objects, supported by radiocarbon dates (Fig. 2). The tin ingots are the subject of this paper whilst the

Table 1 Weight and dimensions of the tin ingots studied.

Reg. No Shape Weight (g) Length (mm) Width (mm) Thickness (mm)

Salcombe 2010,8032.295 Round and plano-convex 9166 228 219 114 2010,8032.296 Oval with plano-convex profile 255 92 62 30 2010,8032.297 Irregular 131 87 55 23 2010,8032.298 Irregular 25 37 30 12 2010,8032.299 Irregular, flat 202 93 64 19 2010,8032.300 Oval with plano-convex profile 366 125 64 32 2010,8032.301 Irregular, flat 377 122 92 20 2010,8032.302 Irregular, flat 21 37 24 7 2010,8032.303 Irregular 14 10 22 7 2010,8032.304 Oval 258 108 58 20 2010,8032.305 Irregular 287 96 77 32 2010,8032.306 Folded 329 90 66 46 2010,8032.307 Irregular 16 38 24 10 2010,8032.308 Irregular 37 43 37 11 2010,8032.309 Oval with plano-convex profile 314 105 67 21 2010,8032.310 Irregular with plano-convex profile 359 111 82 17 2010,8032.311 Irregular, flat 196 118 70 7 2010,8032.312 Relatively flat, folded over 517 135 89 31 2010,8032.313 Oval with plano-convex profile 1003 165 98 34 2010,8032.314 Oval with plano-convex profile 184 81 52 23 2010,8032.315 Oval with plano-convex profile 682 129 66 36 2010,8032.316 Oval with plano-convex profile 1257 185 10 25 2010,8032.317 Circular with plano-convex profile 600 95 90 20 2010,8032.318 Oval with plano-convex profile 368 86 72 28 2010,8032.320 Roundish with flat base 1194 160 140 20 2010,8032.321 Roundish with flat base 169 64 50 24 2010,8032.322 Irregular 116 60 56 24 2010,8032.323 Roundish 8 12 8 2010,8032.329 Possible oval die mark on one side 5 18 14 6 2013,8032.1 Oval with plano-convex profile 645 120 90 20 2013,8032.2 Oval 11 31 21 7 2013,8032.3 Oval, folded over 160 80 45 28 2013,8032.4 Irregular 19 52 34 4 2013,8032.5 Thin, largely corrosion products 4 4 3 4 2013,8032.6 Oval 19 45 (diameter) 5 2013,8032.7 Irregular 97 66 50 16 2013,8032.8 Plano-convex 97 78 45 21 2013,8032.9 Plano-convex 675 112 83 23 2013,8032.10 Relatively flat 136 95 48 8 2013,8032.11 Oval 1147 109 95 67 Erme Estuary 2013,8031.1 Plano-convex 789 110 120 30 2013,8031.2 Plano-convex 669 135 115 31 Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92 83 copper/copper alloy ingots, the gold ornaments and the bronze products. tools and weapons will be studied in subsequent papers. All finds have been acquired by the British Museum, are registered and have 2.2. ICP-MS and ICP-AES procedure been catalogued on Collections Online (http://www. britishmuseum.org/research/collection_online/search.aspx? The alloy composition was determined using ICP-MS and searchText¼Salcombe). inductively coupled plasma atomic emission spectroscopy (ICP- Due to their extreme rarity and morphological simplicity, the tin AES) at the Natural History Museum, London using an Agilent ingots are not typologically diagnostic and, whilst they are more 7700x ICP mass spectrometer and Thermo Scientific iCap 6500 Duo common, neither are the copper/copper alloy ingots (Bachmann ICP spectrometer, respectively. The samples (4e25 mg) were et al., 2004). The bronze rapiers and palstaves as well as the gold weighed to ±0.01 mg, digested in 1 ml of concentrated HCl (SpA™ twisted torc fragments and twisted wire bracelets all indicate a grade, ROMIL Ltd) with the addition of several drops of HNO3 ® Middle Bronze Age Penard phase (c. 1300e1150 BC) date (see Col- (SpA™ grade, ROMIL Ltd) and H2O2 (Merck, Suprapur ), and made lections online). However, the Ewart Park type bronze sword can up to 25 ml with ultra-pure water. Only tin (Sn) and sulphur (S) only be placed in the Late Bronze Age Ewart Park phase (c. concentrations are reported based on the ICP-AES analysis, the rest 1000e800 BC). The rarity of any terrestrial metal ingots in south- of the elements were determined by ICP-MS. Based on the analysis west England during the earlier date range, as opposed to their of tin in CRMs (Tin with impurities; MBH Analytical Ltd) the relative ubiquity in the later date range (see Pearce, 1983; Knight analytical accuracy for tin (Sn) is within 0.6% (relative), for iron (Fe) et al., 2015 for a comprehensive Bronze Age metalwork catalogue e 3%, nickel (Ni) e 7%, copper (Cu) e 2%, zinc (Zn) e 3%; arsenic for southwest England), is not sufficient grounds to propose a finer (As), silver (Ag), indium (In), lead (Pb), bismuth (Bi) e 1%, antimony temporal resolution for the tin ingots. Hence, whilst the tin ingots (Sb) e 2% and gold (Au) e 13%. have an overall date range of c. 1300e800 BC, they could either be c. 1300e1150 BC or c. 1000e800 BC based upon the typo-chronology 2.3. Metallography of the two groups of potentially associated bronze and gold metal objects. Following the compositional analysis, metallurgical samples The Salcombe tin ingots provide a very rare opportunity to were taken from Salcombe ingots 2010,8032.297, 302, 306, 308, analyse directly the Bronze Age ‘tin trade’. The tin ingots vary in size 310, 311, 313 and 323 in an attempt to cover ingots with different and weight as well as in shape although they are generally bun- sizes, shapes and variable impurity levels, and also from the two shaped and most of them are original in size and complete Erme Estuary ingots recently donated to the British Museum (Table 1). The surface of these ingots is bumpy and covered with (2013,8031.1 & 2). corrosion products. Compositional analysis was carried out on all The metallographic samples were taken using an Isomet dia- but one of the Salcombe ingots (2013,8032.5 which appeared to mond saw. The sections were mounted in epoxy resin, ground and have completely corroded), i.e., a total of 39 pieces. Two morpho- then polished using diamond paste to a finish of 1 mm. Scanning logically comparable tin ingots of the 44 found by the South West electron microscopy coupled with energy dispersive X-ray spec- Maritime Archaeology Group in the Erme Estuary e also known as trometry (SEM-EDS) was used for the study of inclusions in the Bay (Fox, 1995, 1996) e were donated to the British metals as well as the surface corrosion layers. The SEM-EDS analysis Museum and analysed for comparison. Following the composi- was carried out using a Hitachi S-3700N Variable Pressure SEM tional analysis, metallurgical samples were taken from eight Sal- with an Oxford INCA Energy system, running at an accelerating combe ingots to cover those with different sizes, shapes and voltage of 20 kV at low vacuum (50 Pa) with a working distance of variable impurity levels and also from the two Erme Estuary ingots 10 mm. After examination of the inclusions, the polished sections for microstructural study. The present study is the first insight into were etched using nital (2 ml nitric acid in 100 ml ethanol) in an the pattern of trace and ultra-trace impurities in ancient tin ingots attempt to reveal the metallographic structure of the metals. employing a very sensitive analytical technique (inductively coupled plasma mass spectrometry; ICP-MS) combined with 3. Results metallographic study. This paper will investigate: the purity of the tin; whether there is significant variation in the composition be- 3.1. Chemical composition tween the ingots; and whether the compositions connect them to any analysed tin samples found elsewhere. It will also place the tin The ICP-MS analyses (Table 2) show that all the tin ingots ana- ingots from Salcombe within the context of current evidence lysed are unalloyed tin with very low levels of impurities, typical of relating to Bronze Age tin production and movement in Europe. The most of the early tin ingots as claimed by Tylecote (1986). The low difficult question of provenance will be addressed using lead and total for some of the samples may be due to corrosion products tin isotope analysis (cf. Haustein et al., 2010) in a future study. present in the samples, as also seen in some of the metallurgical sections taken from the ingots. Archaeological tin finds are rare and 2. Experimental compositional analysis of them is even rarer. Thirty two Uluburun tin ingots analysed by ICP-AES showed they were also quite pure 2.1. Sampling (Hauptmann et al., 2002). A few tin ingots at Hishuley Carmel and Kfar Samir from under water off the coast of Israel analysed by A sample of around 20 mg was taken from each ingot by drilling Begemann et al. (1999) and three Bronze Age tin torcs from Kil- using a 1 mm high speed steel drill bit. To obtain uncorroded sallagh, Co. Longford of Ireland analysed by Cahill (2009) also interior sample of metal for a reliable determination of the alloy showed very pure tin. During the excavations at the bank of Lake composition, the drillings of the corroded surface were discarded Sevan, Armenia many tin-containing objects dated 1400e1200 BC until shiny metal turnings appeared. Tin is very soft, which made were found, of which 14 were subjected to spectral analysis. While the drilling very difficult. Thicker areas appeared to be corrosion some of the objects are reported to be alloys of tin and lead, five out ‘warts’; therefore, most drillings were taken from the sides of the of seven analysed tin buttons are relatively pure tin (0.01e0.35% Pb ingots at thinner areas. The discarded drillings were saved for X-ray and 0.03e0.25% Fe being the major impurities) (Kashkay and diffraction (XRD) analysis to identify the surface corrosion Selimkhanov, 1973; Selimkhanov, 1978). Two tin ingots from 84 Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92

Table 2 Bulk chemical composition of tin ingots determined by ICP-AES and ICP-MS (wt.% for tin and mgg 1 for other elements).

Sample Sn S Mn Fe Co Ni Cu Zn As Ag In Sb W Au Pb Bi U Total %

Salcombe 2010,8032.295 94.1 538 4.2 2065 <8 <10 3.5 18.1 7.15 0.16 13.9 6.55 <0.5 2.15 12.0 13.4 <0.07 94.4 2010,8032.296 100.3 <44 <1.8 86.2 <8 <10 7.2 <2 35.0 <0.1 21.6 46.4 <0.5 <0.5 13.8 31.3 <0.07 100.3 2010,8032.297 98.9 <42 3.6 52.1 <8 <10 2.2 <2 19.5 <0.1 30.1 64.0 <0.5 <0.5 26.4 83.2 <0.07 98.9 2010,8032.298 99.4 <113 <1.8 126 <8 <10 <1.2 <6 14.3 <0.1 29.6 90.0 <0.5 <0.5 27.0 79.4 <0.07 99.5 2010,8032.299 99.5 <57 <1.8 88.4 <8 <10 <1.2 <2 17.4 <0.1 31.1 65.2 <0.5 <0.5 26.7 83.2 <0.07 99.5 2010,8032.300 96.0 <42 <1.8 55.3 <8 <10 <1.2 <2 10.1 0.10 9.87 9.13 <0.5 <0.5 7.08 4.50 <0.07 96.0 2010,8032.301 100.8 <54 7.1 99.4 <8 <10 <1.2 <6 16.1 0.43 33.5 76.8 <0.5 <0.5 30.5 76.7 <0.07 100.8 2010,8032.302 100.9 <185 <1.8 31.4 <8 <10 8.1 10.0 8.97 <0.1 17.9 16.6 <0.5 <0.5 8.86 5.78 <0.07 100.9 2010,8032.303 94.6 <113 2.9 68.7 <8 <10 6.7 <6 5.99 <0.1 11.9 12.9 <0.5 <0.5 6.32 4.61 <0.07 94.7 2010,8032.304 97.4 <40 <1.8 80.2 <8 <10 4.4 <2 21.6 <0.1 5.11 4.10 <0.5 <0.5 12.8 32.7 <0.07 97.4 2010,8032.305 96.7 562 6.0 77.2 <8 <10 5.9 <6 19.3 1.34 13.2 6.76 <0.5 <0.5 19.1 33.7 0.11 96.8 2010,8032.306 99.6 <130 <1.8 43.8 <8 <10 <1.2 <6 6.59 <0.1 12.5 12.7 <0.5 <0.5 6.16 4.60 <0.07 99.6 2010,8032.307 97.9 <58 <1.8 79.8 8.1 <10 2.8 <6 81.2 <0.1 33.2 145 <0.5 <0.5 60.7 120 <0.07 97.9 2010,8032.308 99.2 <53 <1.8 87.4 8.1 <10 24.4 <6 86.0 <0.1 36.8 151 <0.5 <0.5 70.4 128 0.09 99.2 2010,8032.309 99.8 <58 <1.8 58.4 <8 <10 83.1 <6 8.50 <0.1 17.3 15.1 <0.5 <0.5 6.77 4.45 <0.07 99.8 2010,8032.310 96.8 <104 16.8 1461 <8 <10 5.3 <6 7.76 <0.1 13.4 15.8 <0.5 <0.5 5.25 4.66 <0.07 97.0 2010,8032.311 99.9 <174 <1.8 70.1 <8 <10 <1.2 <6 6.64 <0.1 15.5 11.07 <0.5 <0.5 5.03 4.97 <0.07 99.9 2010,8032.312 99.2 <36 <1.8 60.7 <8 <10 28.8 <2 9.55 <0.1 11.0 9.15 <0.5 <0.5 5.84 4.56 <0.07 99.2 2010,8032.313 99.2 <95 <1.8 131.2 <8 <10 <1.2 <6 8.17 <0.1 13.9 289 <0.5 <0.5 4.97 3.22 <0.07 99.3 2010,8032.314 100.1 <66 <1.8 188.8 <8 <10 <1.2 <6 8.22 <0.1 16.6 12.0 <0.5 <0.5 8.69 4.48 <0.07 100.1 2010,8032.315 97.9 <41 <1.8 124.8 <8 <10 2.9 <6 11.9 <0.1 10.7 5.55 <0.5 <0.5 11.3 46.0 <0.07 97.9 2010,8032.316 101.1 <44 <1.8 54.5 <8 <10 1.8 19.2 7.53 <0.1 20.2 8.68 <0.5 <0.5 12.8 6.50 <0.07 101.1 2010,8032.317 100.6 <46 <1.8 431 <8 <10 1.8 <6 8.27 <0.1 22.0 277 <0.5 <0.5 8.34 3.20 <0.07 100.7 2010,8032.318 100.0 <64 11.0 113 <8 <10 5.1 13.6 19.3 <0.1 12.7 6.31 <0.5 <0.5 17.0 31.0 <0.07 100.1 2010,8032.320 99.2 <29 <1.8 48.9 <8 <10 <1.2 <6 12.5 <0.1 29.9 233 <0.5 <0.5 8.37 3.60 <0.07 99.2 2010,8032.321 100.0 <30 <1.8 73.4 <8 <10 3.8 <6 8.85 <0.1 14.9 12.2 <0.5 <0.5 10.4 4.32 <0.07 100.0 2010,8032.322 101.4 <44 <1.8 269 9.3 <10 <1.2 <6 34.4 <0.1 40.3 140 <0.5 <0.5 30.0 49.2 <0.07 101.5 2010,8032.323 100.3 <78 <1.8 162 <8 24.0 2742 <6 29.0 0.41 6.71 25.4 <0.5 2.36 87.2 11.5 <0.07 100.6 2010,8032.329 98.6 117 4.0 251 <8 <10 286 18.8 21.6 0.61 34.9 9.69 <0.5 0.70 7.19 15.2 0.18 98.6 2013,8032.1 98.0 <36 4.0 103 <8 <10 19.8 <2 13.2 <0.1 7.08 13.3 <0.5 <0.5 13.4 6.54 <0.07 98.0 2013,8032.2 97.4 <44 <1.8 100 <8 <10 4.7 <2 16.5 <0.1 26.7 66.5 <0.5 <0.5 18.4 83.1 <0.07 97.4 2013,8032.3 96.6 <41 2.0 143 <8 <10 15.7 2.3 9.76 <0.1 11.2 9.73 <0.5 <0.5 92.3 5.17 <0.07 96.7 2013,8032.4 93.0 82 12.4 462 <8 <10 54.5 <2 7.64 0.14 4.47 11.5 <0.5 <0.5 4.99 5.02 0.17 93.1 2013,8032.6 94.1 <46 5.2 575 <8 <10 6.8 <2 7.79 <0.1 5.35 9.72 0.91 <0.5 4.09 5.46 0.11 94.2 2013,8032.7 97.0 60 <1.8 70.3 <8 <10 32.5 <2 11.1 <0.1 4.80 8.35 0.65 <0.5 14.7 5.65 <0.07 97.0 2013,8032.8 97.0 <42 <1.8 122 <8 <10 14.5 <2 58.9 0.15 24.8 79.9 <0.5 <0.5 36.5 65.3 <0.07 97.0 2013,8032.9 97.1 48 <1.8 735 <8 <10 26.9 16.4 45.0 <0.1 14.2 101 <0.5 <0.5 16.7 26.5 <0.07 97.2 2013,8032.10 96.5 92 5.9 538 <8 <10 3.6 <2 9.65 <0.1 11.6 10.8 0.87 <0.5 5.87 4.76 <0.07 96.6 2013,8032.11 98.7 293 <1.8 143 <8 <10 66.2 11.3 17.3 <0.1 25.4 68.6 0.73 <0.5 31.6 75.7 <0.07 98.8 Min 93.0 <29 <1.8 31.4 <8 <10 <1.2 <2 5.99 <0.1 4.47 4.1 <0.5 <0.5 4.09 3.2 <0.07 Max 101.4 562 16.8 2065 9.3 24.0 2742 19.2 86 1.34 40.3 289 0.91 2.36 92.3 128 0.18 Mean 98.3 244 89* 19.2 18.4 55.3 30.3 Median 98.9 100 5* 11.9 14.9 13.3 6.54 Erme Estuary 2013,8031.1 94.3 123 11.4 2288 <8 <10 37.3 4.0 15.4 0.111 20.9 62.6 13.7 <0.5 12.5 34.4 0.08 94.6 2013,8031.2 98.1 <47 <1.8 107 32.7 60.1 22.6 <2 39.6 0.222 16.8 13.9 0.82 1.03 4.63 1680 <0.07 98.3

Note: * Estimated as being equal to or lower than this value.

Bigbury Bay, South Devon were reported to have been analysed Uluburun ingots is generally lower than in the Salcombe ingots using electron probe micro analysis (EPMA) and revealed that both with the distribution being shifted to lower level (median is are of about 99% purity (Fox, 1995). However, the data of the Big- 55 mgg 1). While only one Erme Estuary ingot out of two analysed bury tin ingots cannot be compared with the Salcombe analysis in this study contains higher iron (2065 mgg 1), three more ingots reported here, because 1) the date of the Bigbury tin ingots could from this site were previously analysed by Craddock and Hook range from the British Iron Age to the post-Roman epoch: 500 BC e (1993) using ICP-AES and reported to contain 0.136, 0.40 and AD 600 (Fox, 1995, 1996); and 2) the EMPA data is not directly 1.07% iron, respectively, which are significantly higher than that of comparable with the bulk analysis such as solution-based ICP-MS the Salcombe ingots (Fig. 3a). analysis. For the purpose of comparison between the tin ingots from different sites one Uluburun ingot (KW3935) containing un- 3.2.2. Lead usually high amount of antimony (0.15%) and silver (0.024%) rela- The Salcombe and Erme Estuary ingots have very low lead tive to other Uluburun tin ingots is excluded from all calculations, levels, lower than 40 mgg 1 in 90% of the Salcombe ingots (Table 2). thus from histograms of trace element concentrations (Fig. 3). This is consistent with the lead contents of three tin objects from Flag Fen, England and two unalloyed tin objects from Hauterive- 3.2. Impurity patterns Champreveyres, Switzerland (18e35 mgg 1) analysed by ICP-MS by Northover and Gillis (1999). On the other hand, even though a 3.2.1. Iron median concentration for lead in Uluburun tin ingots is estimated Iron is present at low levels in the Salcombe ingots with a me- to be as low as 70 mgg 1, about a third of them contain lead at dian concentration being 100 mgg 1 and 87% of the ingots contain concentrations above 500 mgg 1 (up to 0.26%) (Fig. 3b), perhaps iron at concentrations below 500 mgg1. Iron concentration in more resembling Armenian unalloyed tin objects (Kashkay and Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92 85

Fig. 3. Histograms of trace element concentrations in tin ingots from Salcombe and Uluburun as well as Erme Estuary (only for iron). 86 Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92

Selimkhanov, 1973) than European finds. Recent study of Bronze Age tin rings (speculated to have functioned as ingots) from the Tollense valley in northeastern Germany by micro X-ray fluores- cence (m-XRF) (Krüger et al., 2012) revealed that they have lead contents of about 1.4%. A Late Bronze Age tin ingot from Sursee- Gammainseli in Switzerland was also found to contain approxi- mately 1.5% lead (Nielsen, 2014). A tin ring-shaped rod (T1:60) from the Scandinavian Bronze Age context was found to contain 0.77% lead, 0.12% antimony and 0.13% copper by SEM-EDS (Ling et al., 2014). Although XRF data (for Tollense tin), SEM-EDS data (for Scandinavian tin) and the data for Sursee tin (for which the analytical method was not specified) cannot be directly compared with the bulk ICP-MS data, such significant lead contents indicate a very different source of tin from either the Salcombe or the Ulu- burun tin ingots.

3.2.3. Antimony Average concentrations of antimony in the Salcombe ingots and the Uluburun ingots are very close to each other (around 55 mgg 1). Fig. 5. SEM image of Erme Estuary ingot 2013,8031.1, showing surface crust consisting However, the range of antimony concentrations in the Salcombe of a mixture of SnO, SnO ,SneOeCl phases and residual metallic tin. 2 ingots is broad (4e289 mgg 1) and the distribution is skewed so that about 60% of them contain antimony at concentrations below 25 mgg 1 and a median value is 13.3 mgg 1; while this is not the 3.2.6. Copper case for the Uluburun ingots (as mentioned earlier, one Uluburun The Salcombe ingots generally contain less copper (70% of ingots ingot (KW3935) containing unusually high amount of antimony is with less than 10 mgg 1; its median concentration is less than excluded from all calculations) (Fig. 3c). Both analysed Erme Estu- 5 mgg1) than the Uluburun ingots (median concentration is ary ingots contain antimony at similarly low levels. 40 mgg 1; Fig. 3f). However, one ingot (2010.8032.323) is copper- rich (0.27% Cu) and is also slightly enriched in gold and lead. 3.2.4. Silver All the Salcombe ingots (and the two analysed Erme Estuary 3.2.7. Indium ingots) contain only ultra-trace amount of silver (less than Although indium is known to accumulate in tin deposits, little 1.4 mgg 1 and in 80% of cases below the limit of quantification of reliable data exist so far for the concentration of this element in 0.1 mgg 1). This seems to be in contrast to Uluburun ingots, in ancient tin. Tin minerals from Cornwall-type deposits may typically which the reported concentrations of silver are up to 90 mgg 1 e m 1 contain indium at levels of 200 700 gg in cassiterite (SnO2) and (Fig. 3d) and even reaching 240 mgg 1 in an antimony-rich ingot 1 2100 mgg in stannite (Cu2FeSnS4)(Briskey, 2005). Our ICP-MS (KW3935) not considered here. analysis (using 113In) shows that the concentrations of indium in the Salcombe and Erme Estuary ingots are in the range of 3.2.5. Arsenic 4.5e40.4 mgg 1 with a median concentration of 14.9 mgg 1. Pre- Over 90% of the Salcombe ingots contain arsenic at concentra- viously published ICP-MS data on Bronze Age pure tin objects tions below 50 mgg 1 and all the Uluburun ingots and the analysed (Northover and Gillis, 1999) are probably subject to significant Erme Estuary ingots do not exceed this level of concentrations overestimation of indium due to an isobaric interference of the (Fig. 3e). 115Sn (0.34% isotopic abundance) on 115In measured, which cannot

Fig. 4. SEM image of Salcombe tin ingot 2010,8032.311, showing surface oxidation Fig. 6. SEM image of Salcombe ingot 2010,8032.313, showing small pores present in crust and unaltered metal remaining in the centre. the metal.. Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92 87

3.3. Microstructure

3.3.1. Surface corrosion layers All of the samples examined were covered with corrosion products on the surface and have unaltered metal remaining in the centre (Fig. 4). The surface crust varies in thickness, ranging from a thin layer of less than 200 mm to almost the entire thickness of the ingots in some cases with one ingot (2013,8032.5) appearing completely corroded. SEM-EDS analysis of the metallurgical sam- ples identified a layer of the SneOeCl phase, in most cases abhurite [Sn21Cl16(OH)14O6], normally formed next to unaltered metal fol- lowed by a layer of SneO phase, in most cases romarchite (SnO), which was confirmed by XRD. A thin layer or agglomerates of a seemingly different phase with potentially lower Sn/O ratio was sometimes observed at the boundary between SneOeCl phase and SneO phase and may be composed of cassiterite (SnO2)(Dunkle et al., 2004). The surface crust does not always have a clear layered structure; it often consists of a mixture of tin oxides as well as islands of metallic tin (Fig. 5). A mixture of Sn21Cl16(OH)14O6, SnO Fig. 7. SEM images of the Erme Estuary tin ingots, showing iron-tin (FeeSn) inter- and SnO2 was indeed identified by XRD in the drillings discarded metallic compounds (large dark features) present in the metal. during sampling for chemical composition analysis. The pattern of corrosion and the chemical composition of phases resemble closely be resolved by quadrupole-based instruments. Similarly, the study the products formed during the corrosion of pewter artefacts from of Mediterranean tin scraps (Valera and Valera, 2003) does not give the Queen's Anne Revenge (AD 1718) (Dunkle et al., 2003) and other fi any technical details on the ICP-MS method and indium concen- marine nds (Dunkle et al., 2004). trations reported might also be suffering from tin or cadmium (Cd) isobaric interferences. 3.3.2. Metallic tin The microstructure of the metallic tin of the ingots shows ho- mogeneous compositions with mini pores of generally less than 1 mm in diameter (Fig. 6) or even smaller in some of the samples, e.g. no. 2010,8032.308. The tin ingots (as their compositions showed) appeared generally quite pure; however, inclusions are 3.2.8. Bismuth found in the microstructure of all ingots except 2013,8032.297 & All the Salcombe ingots contain bismuth at concentrations 306. below 130 mgg 1, with over 50% ingots being of less than 10 mgg 1 and a median concentration of 6.54 mgg1. Bismuth was not 3.3.3. Inclusions in the metal generally determined in the Uluburun ingots so comparison is not Tin-iron intermetallic inclusions are known in archaeological tin possible. One out of the two Erme Estuary ingots analysed here has (Northover and Gillis, 1999). Most ingots studied here (Salcombe a much higher bismuth content (1680 mgg 1). ingots 2010,8032.302, 308, 310, 311, 313 and Erme Estuary ingots Nickel, cobalt (Co) and zinc are mostly below detection limits in 2013,8031.1 & 2) contained 1 mme100 mm crystal-like grains with m 1 both the Salcombe and Uluburun ingots, and below 30 gg in a approximate composition FeSn2 e ‘the commonest and best few cases when detected. known’ of iron-tin intermetallic compounds (Louis, 1911). The largest number of FeSn2 inclusions (known as ‘hard head’)is observed in the Erme Estuary ingot 2013,8031.1 with 0.23% iron in bulk composition (Fig. 7). The same ingot also contains less abun- dant grains of an intermetallic with a composition close to SnFe, which was not found in any other ingots (containing less iron in bulk chemical composition according to the ICP-MS analysis). The FeSn2 inclusions seem to be resisting oxidation better than the pure tin matrix (Northover and Gillis, 1999) and were found in the ‘romarchite’ zone of tin oxidation products in several ingots, while fragments of pure tin remain only in the ‘abhurite’ layer, which may have formed as the first stage of tin corrosion (Dunkle et al., 2004). All tin ores contain appreciable amount of iron, which can be easily removed by re-melting or refining when forming as ‘hard head’,so the iron content in metallic tin is a factor of the smelting and more specifically of the refining. A recent study of tin ingots from the Gresham ship suggests that the local enrichment in iron may derive from the material of the mould where the ingots were cast (Birch et al., 2014). Ingot 2010,8032.323 is unusual among the Salcombe tin ingots due to its high bulk copper content (0.27%). Copper is found to segregate into inclusions that are probably too small for quantita- Fig. 8. SEM image of Salcombe ingot 2010,8032.323, etched, showing copper-tin e (CueSn) intermetallic compounds (large dark spots) present in the metal. Uneven tive SEM-EDS analysis, however, copper-tin (Cu Sn) intermetallic brightness of the tin matrix is the result of etching. compounds e the phases widely known in tin alloys (Barry and 88 Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92

Thwaites, 1983) e are observed (Fig. 8) and some of them were Salcombe and Erme are local it is likely to be placers in the found to also contain iron. This type of inclusions has not been South area that would be sampling a number of deposits found in any other ingots in this study. exposed by periglacial conditions after last Ice Age (Chris Stanley, Very small grains of hexagonal shape with the composition of pers. comm.). approximately SnCu0.1S were observed in the Erme Estuary ingots There is more direct evidence for Bronze Age tin smelting in 2013,8031.1 & 2 and the Salcombe ingots 2010,8032.310, 311 & 313. southwest England. Fox (1957) reported potential signs of tin Several small (c. 2.5 mm) bismuth-rich inclusions are found in metallurgical activity during excavations at the settlement site of the oxidation crust of Erme Estuary ingot 2013,8031.1 characterised Dean Moor (upper part of the river Avon, only about 4 km from the by unusually high bulk bismuth content (0.17%). Due to the small river Erme) probably dating to the Late Bronze Age: a pebble of size of the inclusions it was not possible to tell whether they are cassiterite and a small bead of unusual reddish tin slag e not tin composed of pure bismuth or of a BieSn intermetallic. Although metal as reported elsewhere (Pearce, 1983; Penhallurick, 1986) e such inclusions were not found in the unaltered metal, it is likely 3.2 mm in diameter was found in one of the excavated settlements that they are original features of this ingot. They may have pre- (Hut 5B) (Malham, 2010). Two cassiterite pebbles and six tin slag dominantly populated one side of the ingot due to a large difference fragments e the latter representing a secondary deposition with a in density between bismuth and tin and remained unaltered during bronze dagger e as well as a seventh from the soil above were also tin oxidation due to their higher resistance to corrosion (Northover found at a ring-banked enclosure dating to c. 1500 BC at Caerloggas and Gillis, 1999). Down, Cornwall (Miles, 1975; Tylecote, 1975; Biek, 1979; Salter, Arsenic-rich inclusions were not identified in the Salcombe in- 1997; Malham, 2010). Across the , the analysis of got 2010,8032.308 which contains more arsenic (86 mgg 1) than tin smelting slag at the site of St Renan, Finistere dating to any other ingots, although a couple of very small arsenic-rich grains 1387e1084 cal BC (Giot and Lulzac, 1998; Mahe-le Carlier et al., were found in the samples of 2010,8032.311 and 2010,8032.323. 2001) provides the only evidence for tin smelting in northwest France. Very few tin slags have ever been found throughout Bronze 4. Discussion Age Europe because the smelting of the tin oxide cassiterite (SnO2), the way metallic tin was produced during the Bronze Age, produced 4.1. Tin production virtually no slag, since alluvial cassiterite is about 80% pure tin (Muhly, 1993). However, the mining of low grade tin ores con- The evidence for Bronze Age tin mining and smelting in taining higher levels of haematite, followed by thorough benefici- southwest England that could have produced the Salcombe tin ation by hand, could also have occurred with similar consequences ingots remains extremely limited. There are no confirmed Bronze for archaeological visibility (Yener and Vandiver, 1993). Age tin mining sites in southwest England with later mining ac- There is certainly growing evidence for Bronze Age copper and tivities up until the 20th century leaving only circumstantial evi- gold exploitation in southwest England. The dating of copper dence (Craddock and Craddock, 1996). The recent comprehensive mining to 1950e1750 BC at Roman Lode, (Juleff and Bray, environmental analyses of tin, lead and copper levels within un- 2007) supports the compositional analyses of copper-alloy ob- disturbed peat bogs on Dartmoor and Bodmin moor indicated only jects by Bray and Pollard (2012) which demonstrate the contem- potential tin extraction from around AD 100 and not earlier porary extraction of copper from southwest England. The (Meharg et al., 2012). However, locally available cassiterite has been exploitation of gold sources in southwest England has been argued found at Bronze Age sites such as the settlement site of Trevisker, on the basis of recent lead isotope analyses of 50 Chalcolithic e Cornwall dating to c. 1700 to 1300 BC which revealed three groups Early Bronze Age (c. 2500e1500 BC) gold objects in Ireland of cassiterite pebbles: 20 in Structure B, two in House A and one in demonstrating non-local sources (Standish et al., 2015). This does House C (ApSimon and Greenfield, 1972) although whilst miner- not mean that gold sources in Ireland were not exploited during alogical identification was performed, no compositional analyses this period e as has been argued for the Mourne Mountains, Ireland were published (Penhallurick, 1986). The discovery of Bronze Age e or that prospecting for gold may also have been accompanied the bronze metalwork in alluvial tin streams (see Pearce, 1983; extraction of tin (Warner et al., 2010a, 2010b). There is also now Penhallurik, 1986 with the bias towards Cornwall rather than widespread evidence for secondary bronze production activities, Dartmoor/Bodmin moor at least partially due to the intensity of usually in the form of mould fragments, in MiddleeLate Bronze Age 18the19th century re-workings) strongly implies that alluvial (c. 1500e800 BC) settlement sites in southwest England (Knight, sources were exploited (cf. Shell, 1979). Haustein et al. (2010) car- 2014; Jones et al., 2015) which reflects broader patterns of mould ried out tin isotope analysis on 50 tin ores from the Erzgebirge deposition across southern England (Brown and Medlycott, 2013). region and 30 tin ores from Cornwall and argued that the tin source for the Nebra sky disc, typologically dated by associated finds to c. 4.2. Tin objects 1600 BC, was probably Cornish. It is hoped that tin isotope analysis to be carried on these Salcombe and Erme Estuary/Bigbury Bay tin The evidence for Bronze Age tin objects in southwest England ingots in the future to answer the question of provenance. beyond the Salcombe tin ingots is only slightly more extensive than With regards to the Salcombe and Erme Estuary tin ingots, the the evidence for tin production. The recent discovery of an excep- Erme river is draining areas very rich in tin (1385e2000 mgg 1 in tionally well preserved cist burial in the peat on Whitehorse Hill, stream sediments; BGS, 2000) so it is not surprising that 16th Dartmoor, Devon dating to c. 1900e1700 BC revealed a young adult century alluvial tin streamworks are known within its valley with a bracelet of 35 small tin studs as well as a cylindrical tin bead (Gerrard, 1996). The stratigraphical and geochemical analysis of a on a composite necklace of amber, Kimmeridge shale and clay palaeochannel in the Erme river indicate that tin extraction in the beads (Jones et al., 2014). The closest surviving contemporary Salcombe vicinity was potentially occurring from at least 4th e 7th parallels for tin ornamentation are found in continental Europe as century AD (Thorndycraft et al., 2004). The modern Salcombe- with the 47 segmented tin beads found in a female grave at Bux- Estuary is unusual because no large river feeds it. Tin heim, Bavaria dating to 2210e1960 BC (Moslein€ and Rieder, 1998) levels in sediments within the Salcombe catchment are not as high and the necklace of 25 tin beads (7 segmented, 18 plano-convex), as in the Erme catchment, but are still elevated in some part of it 13e14 amber beads, one bronze bead and four segmented faience (above 42 mgg 1; BGS, 2000). If the sources of tin ingots from the beads found at Exloo, Netherlands and dated typologically to the Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92 89 earlier 2nd millennium BC (Haveman and Sheridan, 2006). The only tin fragments found in the Nuragic sanctuary of S'Arcu 'e is Forros, other tin bead from Britain in a comparable context was found in an Sardinia reported by Valera and Valera (2003) shows a significantly Early Bronze Age barrow at Sutton Veny G11c, Wiltshire during higher lead content (500e8700 mgg 1) and also higher levels of antiquarian excavations and subsequently lost (Penhallurick, 1986). cobalt, nickel, zinc and copper than the Salcombe ingots. The use of Tin objects remain exceptionally rare, even within the wide di- lead isotope analysis as well as trace element analysis in analysing versity of materials found in Early Bronze Age (c. 2200e1500 BC) the provenance of tin has suggested that the Uluburun tin ingots funerary contexts in Britain (Woodward and Hunter, 2015). The use contain at least two groups, and tin ingots from Hishuley Carmel off of tin as an inlay within other materials in Bronze Age (c. 2200e800 the Israeli coast may have been from the same source as one of the BC) Britain as with the jet button found in the cist burial at Uluburun groups (Stos-Gale et al., 1998) and also that the Sardinian Rameldry, Fife, Scotland dating to c. 2200e1900 BC (Baker et al., tin objects were not produced locally (Valera and Valera, 2003). The 2003) or the MiddleeLate Bronze Age (c. 1500e800 BC) future use of lead and tin isotope analyses could well provide Caergwrle bowl found in northeast Wales (Davis and Townsend, further insights into the provenance of the Salcombe ingots (cf. 2009) is similarly very infrequent. The discovery of potentially Haustein et al., 2010; Standish et al., 2014, 2015). Bronze Age tin ingots in southwest England, some comparable to the rough form found at Salcombe, at sites such as Penwithick, St 4.4. Importance of the Salcombe tin ingots Wenn/Landjew Farm, Tremethack Moor, Burngullow, Vellin Antron Farm and Mabe have unfortunately occurred in unstratified or The morphology of the Salcombe and Erme Estuary/Bigbury Bay poorly recorded contexts (Penhallurik, 1986; Malham, 2010). ingots strongly implies that they were roughly cast in a hollow in The discovery of the 44 tin ingots at Bigbury Bay at the mouth of the ground or perhaps into the sand, thus limiting any typological the river Erme (Fox, 1995, 1996) e of which two ingots feature in distinctions (cf. Timberlake, 1994; Gomez-Ramos, 1993; Le Carlier the analyses in this paper e are also unstratified finds with no et al., 2014; Nessel, 2014). There is a very wide and uneven distri- datable or typologically diagnostic associations. It is certainly bution of weights in the tin ingots, although most of them are possible that the ingots could date to the Bronze Age (cf. SWAG, original in size and complete and not broken/fragmented (Table 1). 1993), rather than the Iron Age (cf. Fox, 1995, 1996), as the form Two copper alloy rectanguloid blocks have been found at Salcombe of the ingots is inconclusive. e one smooth weighing 44.7 g (Needham et al., 2013) and one with wavy mouldings weighing 29.8 g (2010,8032.35) e have strong 4.3. Compositions of tin from different sites parallels in weights found in MiddleeLate Bronze Age contexts in western central Europe (Pare, 1999, 2013). Whilst the issue of It is difficult to make a meaningful comparison of the Salcombe weight measurement will not be analysed in depth in this paper, with Bigbury Bay/Erme Estuary ingots because of the much smaller there is no straightforward proportional correlation between the sample size in the latter. The two Erme Estuary ingots analysed in weights of these rectanguloid blocks and the tin ingots, nor is there this study do not necessarily belong to the same workshop/ore any obvious regularity within the weights of the tin ingots them- source based on both the significantly different bulk contents of selves. The weights of the tin ingots also do not correlate to Bronze iron and bismuth and inclusions in their microstructures. One ingot Age weight units identified in continental Europe e such as the is significantly enriched in iron and the other in bismuth and 48.8 g and 104 g for the Late Bronze Age in France and Switzerland slightly in cobalt and nickel. Even though the bulk concentration of (Pare, 2013) or 61.3 g for central Europe during the 13th century BC iron can reflect the degree of tin refining it may depend on the (Pare, 1999). However, there can be little doubt that weights were representativeness of a sample obtained by drilling as intermetallic being measured across Bronze Age Temperate and Mediterranean FeeSn compounds may tend to concentrate in one part of the ingot Europe and that these frequently related to metals (Pare, 1999; (as observed in 2013,8031.1) e potentially due to their higher Pulak, 2000b; Lo Schiavo, 2006; Rahmstorf, 2010; Roscio et al., density (Kwon et al., 2003) e and the results may be biased 2011). depending on what side of the ingot was drilled. If both Salcombe The only potentially comparable Bronze Age shipwreck site to and Bigbury Bay/Erme Estuary tin ingots derive from ores in the Salcombe in northwest Europe is at Langdon Bay, Dover, Kent, same region which is assumed to be southwest England, the dif- southeast England which comprises 360 bronze objects typologi- ference in trace element patterns suggest that they may have been cally dating to the Middle Bronze Age Penard metalwork phase (c. produced by different smelting and refining methods. With the 1300e1150 BC) (Needham et al., 2013). However, there were no tin chemical composition alone it is not possible to identify if objects found at Langdon Bay nor any typologically diagnostic the Salcombe and Bigbury Bay/Erme Estuary ingots have been from Bronze Age tin objects found off the coasts of Britain and the near the same source. Continent (Needham et al., 2013). Whilst tin ingots were recovered The comparison of the Salcombe tin ingot trace element com- from the Bronze Age shipwreck sites at Uluburun (Pulak, 2000a; positions to other analysed Bronze Age tin objects reveals some Hauptmann et al., 2002) and Cape Gelidonya (Bass, 1967, 2010; variation which can provide insights into provenance. All of the Stos-Gale et al., 1998), these site provide insights into the in- published data encompassing the few sites where Bronze Age tin terconnections spanning the Bronze Age palaces, towns, cities and objects have been found and their trace elements determined, states in the eastern Mediterranean, but are of limited relevance for shows that tin found from different regions has different impurity understanding of the smaller-scale Bronze Age farming societies in patterns which will help to lead us to the sources of the tin in the Central, Western and Northern Europe. The shipwreck at Roche- future with more archaeological and scientific data becoming longe, Agde, southeast France, which comprised 32 tin ingots available e with the caveat that the same ore sources may have amongst the c. 1700 objects recovered and dates to c. 600 BC, is variable trace element compositions. Currently, the main difference more closely comparable despite being at least two centuries later in trace elements between the Uluburun and Salcombe tin ingots, and connected to the rapidly changing Mediterranean world the only two sites where large numbers of analyses have been (Hugues, 1965; Bouscaras, 1971). However, this Iron Age assem- carried out, is the contents of lead and silver. This suggests, un- blage remains very poorly published and the tin ingots have yet to surprisingly given the geographical distance between the two sites, be analysed archaeometallurgically. The maritime movement of that these two groups of ingots were smelted from ores of quite copper, tin, bronze and gold throughout Bronze Age Europe re- different composition. The ICP-MS analysis of five Late Bronze Age mains only directly evidenced at a few shipwreck sites (Lucas 90 Q. Wang et al. / Journal of Archaeological Science 67 (2016) 80e92

Pellicer and Gomez-Ramos, 1993) and the presence of tin ingots at comments that greatly improved the quality of the manuscript. We Salcombe makes it unique to northwest Europe. would like to thank Mick Palmer and Jim Tyson of the South West The production and maritime movement of pure tin ingots as Maritime Archaeology Group for providing information on the evidenced at Salcombe is important not only for being very rare Erme Estuary ingots, Craig Williams of the British Museum for Fig.1, direct evidence for the Bronze Age tin trade, it also implies the and Paul Craddock and Duncan Hook of the British Museum and desire to control tin compositions in bronze objects. The implica- Chris Stanley of the Natural History Museum, London for their tion of the 360 Bronze Age bronze objects at Langdon Bay constructive comments on the paper. (Needham et al., 2013) is of an exchange in finished bronze metalwork which can be recycled, but with no real control over the References resulting alloy's composition. This exchange and recycling of bronze in northwest Europe is only partially revealed in the com- ApSimon, A.M., Greenfield, E., 1972. The excavation of the Bronze Age and Iron Age settlement at Trevisker round, St Eval, Cornwall. Proc. Prehist. Soc. 38, 302e381. plexities of cross-channel inter-connections demonstrated in the € e Bachmann, H.-G., Jockenhovel, A., Spichal, U., Wolf, G., 2004. Zur bronzezeitlichen typologies of deposited Middle Late Bronze Age bronze metalwork Metallversorgung im mittleren Westdeutschland: Von der Lagerstatte€ zum (Brandherm and Moskal del Hoyo, 2014; Matthews, forthcoming; Endprodukt. Berichte der Komm. für Archaologische€ Landesforschung Hess. 7 Needham, forthcoming). In contrast, the desired ability to add tin (2002/2003), 67e120. fi Baer, K. E.v, 1876. Von wo das Zinn zu den ganz alten Bronzen gekommen sein mag? is demonstrated by higher tin contents in speci c object types such Arch. für Anthropol. 9, 263e267. as c.10e14% tin found in bronze shields (Uckelmann, 2012; Wang Baker, L., Sheridan, A., Cowie, T., 2003. An Early Bronze Age ‘dagger grave’ from et al., forthcoming) and in cauldrons (Northover, 2010; Wang, Rameldry Farm, near Kingskettle, Fife. Proc. Soc. Antiq. Scot. 133, 85e123. Barry, B.T.K., Thwaites, C.J., 1983. Tin and Its Alloys and Compounds. Ellis Horwood, forthcoming) from c. 1300 BC. Chichester. There is no surviving evidence for any Bronze Age boat at Sal- Bass, G.F., 1967. Cape Gelidonya: a Bronze Age Shipwreck, vol. 57/8. Transactions of combe site. It can only be assumed that either contemporary sewn the American Philosophical Society, Philadelphia. Bass, G.F., 2010. Cape Gelidonya shipwreck. In: Cline, E.H. (Ed.), The Oxford Hand- plank vessels such as found at Ferriby, northeast England (Wright book of the Bronze Age Aegean. Oxford University Press, Oxford, pp. 797e803. et al., 2001; Van der Noort et al., 2014) or Dover, southeast En- Begemann, F., Kallas, K., Schmitt-Strecker, S., Pernicka, E., 1999. Tracing ancient tin gland (Clark, 2004), or log boats as found at Carpow, southeast via isotope analyses. In: Hauptmann, A., Pernicka, E., Rehren, T., Yalçin, Ü. (Eds.), Scotland (Strachan, 2010) were involved in transporting the objects The Beginnings of Metallurgy. Der Anschnitt 9. Deutsches Bergbau-Museum, Bochum, pp. 277e284. recovered. The locations of the departure and destination are un- BGS (British Geological Survey), 2000. Regional Geochemistry of Wales and West- known with the debate complicated by the high probability that Central England: Stream Sediment and Soil. BGS, Keyworth, Nottingham. two temporally distinct Bronze Age shipwrecks can be identified at Biek, L., 1979. The archaeological tin and iron cycles. In: Scollar, I. (Ed.), Proceedings of the 18th International Symposium on Archaeometry and Archaeological Salcombe. It cannot be simply assumed that the tin production site Prospection, Bonn, 14-17 March 1978 (Archaeo-Physika 10). Rheinland-Verlag, for the ingots was nearby despite the geological potential within Cologne, pp. 75e81. the vicinity of the Erme Estuary (cf. Kassianidou, 2003 on the Birch, T., Charlton, M.F., Biggs, L., Stos-Gale, Z.A., Martinon-Torres, M., 2014. The cargo. In: Milne, G., Sully, D. (Eds.), The Gresham Ship Project; a 16th-Century interpretation of the production sites for the Uluburun and Haifa Merchantman Wrecked in the Princes Channel, Thames Estuary, Contents and ingots). The Scandinavian Bronze Age tin ring-shaped rod (T1:60) Context, vol. II. Archaeopress, Oxford, pp. 53e69. was found to be fully consistent with the lead isotope compositions Bouscaras, A., 1971. L'epave des bronzes de Rochelongues. 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